Electrodeposition of nickel



Patented May 5, 1953 li'loyd BiPortzer and Vtilliam 1G. Leitenberger, Cleveland, Ohio NoaDrawing. Application May 31, 1951, S'erialNo. 229,261

El 'Glain'is.

This invention "relates to the electrodeposition of metals and in particular relates to a brightenins additive for useirrtlie' electrode-position of bright nickel from a nickel electrolyte.

In the past selectionofa brightener for use in the electrodeposition" of' bright nickelhasbeenpredicatedupon the samemeeting severalrm quirements' relative to operability ina standard Watts bath.

First; it" was' important that the brightener used be soluble in the-entire-solutionso that theformationof an insoluble" precipitate; which would be" detrimental totheoperation the bath, would be avoided;

Secondgit was importantuto.ascertain that the" use of the: brightener would notainterfere withthe action: of. additional additives used to: effec== tuate separate and distinctfiunetions; such"v as levelling;

Lastly, it was. important. that. the brighten'er selected be operable. within the entire bath to efiectuate ia'ktluly lustrousnand bright! deposit on the article being plated.

Becauseofrthe rigidity of the aforementioned: requirements, all known brighteners now commercially available on the market, have been;-

found unsatisfactory forone, reason or another. Either they: were insoluble in the overalltbath, interfered with the action of the other additives,

or because ofythese other additives =presentinthe bath, were inoperable to give a truly. brightand lustrous plate.

Further difiiculty"has been'encountered in all,

ence of: streaks, which? render" the; product: unisatisiactory from as commercial standpoint;

Accordingly; it is? one obi ectw oi; thlS'rlllVGl'ltlOlli to provide a brightening additive which Will-be:-

soluble in nickel electrolyte over-'arelatively wide current density range.

It is a-iurther: object of this invention to providea: brightening additive which can be made compatiblewith a; levelling additive used] in, a

standard Watts. bath.

It is -a' furtherob'ject of this invention to provide a stabilizedrbrightening additive which. will' notfbreakv down under. electrolysis to cause the. formation of an insoluble precipitate;

all)

Other objects o f the-invention will become: ape, parent upon consideration of thefollowing: briefi specification and: the examples used i therein.

Broadly speaking it has been discovered that. ii a1 certain class of i dye compounds: are used in: conjunction with certain other chemical& com? pounds, a highly satisfactory brighteningadditive is: formed; which compound satisie'totorilyimeets: alli the: prerequisites; previously set forth-1 in this regard.

Specifically, it has been found that if triphenylmethane dyes; and in particular triphenylmethane. dyes having an auxochrome. group. therein, are reduced to the leuco state. thereof and then treated with an excessoi: aholding;

agent for, which the oxygen, of, the air has a: greater aiiinity than for said reduced leuco com pound, the resulting compound will give exceptional results when used as abrightening additive in a Watts bath. In essence, the foregoing treatment amountsto a reduction to the leuco A state by onecompound and -a holding-of the'productinthat state by another compound, Trip'h'enyl-- methaneidyes-whichcan bex satisfactorily treated. by. this ldualprocess of-reduction and holding are listed in table A below.

TABEEA Fuchs-inc Pararosaniline Rosaniline Methyl Violet Aniline Blue Iodine Green Aurine-r Acid Fuchsin Thev underlying theory. for this dual i process-or T reduction and holding, stems fronrthe discovery that a relatively rapid reduction :of; the triphenyb methane dye to. the leuco state changes the:.dye from an insoluble compound to a soluble compound capable of userinlanlelectroplating bath. Further treatment in the form of use of a compound wl'iich' will holdthis-'first'-mentioned com pound in" the-leuco state"is necessitated by the fact that unless sO-treated; theleucocompound" will gradually oxidizeand revert -to the originalinsoluble dye-- product, and accordingly be un=-- satisfactory for use in the bath. Experimentation has shown that tl'ie usecf zinc powder and ooqc-agnrecocaw hydrochloric acid is satisfactory toreduce the,

dye to thesleuco state if'the amountsused' are controlled so that the triphenylrnethane dye- Would not be reduced to the point where an..excess of this reducing agent was present in the; form of an insoluble precipitate which would disadvantageously aifect the results obtained from the plating solution. Hence it became manifest that further oxidation that would normally take place must be prevented, or at least compensated for, by the use of compound which would not result in the formation of an insoluble precipitate that would act to destroy the overall solubility of the brightening additive. Best results in this regard could be obtained by using an oxygen containing compound for which the oxygen possessed a greater aflinity than for the reduced leuco compound. In practical application, it was found that use of either sodium hydrosulfite or sodium bisulphite was satisfactory to effectuate the desired holding action, inasmuch as the addition of an excess amount of either one of these compounds did not result in the creation of an insoluble precipitate.

While all of the compounds listed in Table A can be satisfactorily treated as just described, it has been found that certain of the compounds are soluble in the nickel electrolyte without the presence of the reducing and holding agents and accordingly the use of these soluble compounds per se is intended to be within the scope of this invention.

In practice, satisfactory brightening additives for use in the newly discovered process have been prepared by employing the mixture of each of the below listed examples:

Example 1 Pararosaniline grams 450 Zinc powder do 120 Hydrochloric acid cc 200 Sodium hydrosulphite pound 1 Water gal 13 Example 2 Rosaniline "grams" 454 Zinc powder do 120 Sulfuric acid cc 100 Sodium hydrosulphite pound 1 Water gal 13 Example 3 Methyl Violet grams 450 Zinc powder do 120 Sulphuric acid cc 100 Sodium hydrosulphite pound 1 Water gal 13 Example 4 Fuchsin grams- 454 Zinc powder do 120 Sulphuric acid cc 100 Sodium hydrosulphite pound 1 Water gal 13 Example 5 Aniline Blue grams 448 Zinc powder do 120 Hydrochloric acid cc 200 Sodium hydrosulphite pound 1 Water "gal..- 13

Example 6 Iodine Green mgrams" 450 Zine powder do 120 Sulphuric acid cc 100 Sodium bisulphite pound 1 Water gal. 13

4 Example 7 Aurine grams 450 Zinc powder do Hydrochloric acid gal. Sodium bisulphite pound 1 Water gal 13 Nora-The designation of weights employed in the above examples relate only to amounts used in preparing the brightening additive per se, and in no way relate to volumes used in plating baths. In practice, each of the above additives, shown by a specific example, constitutes approximately O.1O.2% of the volume of the plating tank.

Thus it will be seen that use of triphenylmethane dye in conjunction with a reducing agent and a holding agent will result in a brightening additive having the desirable property of being compatible with other additives over a relatively wide current density range.

For the purpose of illustrating how the brightening additives set forth in the above described examples may be satisfactorily utilized to commercially electrodeposit bright nickel, certain electrolytic solutions which have been found to be satisfactory, are described in the below-listed examples.

Example 8 Nickel sulphate 40 oz./gal. Nickel chloride 8 oz./gal. Boric acid 6 oz./gal. Brightening additive (Per Example #2) .15% by volume. pH 4.0. Temperature l35-145 F. Current density 50 amps/sq. ft. Example 9 Nickel sulphate 45 oz./gal. Nickel chloride 8 oz./gal. Boric acid 6 oz./gal. Brightening additive (Per Example #1) 15% by volume. pI-I 4.5. Temperature -145 F. Current density 50 amps/sq. ft.

Example 10 Nickel sulphate 50 oz./ga1. Nickel chloride 10 oz./gal. Boric acid 5 oz./gal. Brightening additive (per Example #3) 20% by volume. pH 4.5. Temperature l35-145 F. Current density 35 amps/sq. ft.

Example 11 Nickel sulphate 40 oz./gal. Nickel chloride 8 oz./gal. Boric acid 6 oz./gal.

Brightening additive (per Example #4) 20% by volume.

pH Temperature l35-l45 F. Current density 35 amps/sq. ft.

a holding agent selected from the group consisting of sodium bisulfite and sodium hydrosulfite.

2. A method of electrodepositing nickel from a nickel electrolyte comprising an aqueous acid solution of a nickel salt, comprising the step of electrolyzing said nickel electrolyte in the presence of a reduced triphenylmethane dye obtained by the reaction of the corresponding triphenyhnethane dye with a reducing agent comprising zinc powder and sulfuric acid, and a holdin agent selected from the group consisting of sodium bisulfite and sodium hydrosulfite.

3. A method of electrodepositing nickel from a nickel electrolyte comprising an aqueous acid solution of a nickel salt, comprising the step of electrolyzing said nickel electrolyte in the presence of a reduced triphenylmethane dye obtained by the reaction of the corresponding triphenylmethane dye with a reducing agent comprising zinc powder and hydrochloric acid and a holding agent comprising sodium bisulfite.

4. A method of electrodepositing nickel from a nickel electrolyte comprising an aqueous acid solution of a nickel salt, comprising the step of electrolyzing said nickel electrolyte in the presence of a reduced triphenylmethane dye obtained by the reaction of the corresponding triphenylmethane dye with a reducing agent comprising zinc powder and hydrochloric acid, and a holding agent comprising sodium hydrosulfite.

5. A method of electrodepositing nickel from a nickel electrolyte comprising an aqueous acid solution of a nickel salt, comprising the step of electrolyzing said nickel electrolyte in the presence of a reduced triphenylmethane dye obtained by the reaction of the corresponding triphenylmethane dye with a reducing agent comprising zinc powder and hydrochloric acid, and a holding agent selected from the group consisting of sodium bisulfite and sodium hydrosulfite.

6. A method of electrodepositing nickel from a nickel electrolyte comprising an aqueous acid solution of a nickel salt, comprising the step of electrolyzing said nickel electrolyte in the presence of a reduced triphenylmethane dye obtained by the reaction of the corresponding triphenylmethane dye with a reducing agent comprising zinc powder and a mineral acid, and a holding agent selected from the group consisting of sodium bisulfite and sodium hydrosulfite.

7. A method of electrodepositing nickel from a nickel electrolyte comprising an aqueous acid solution of a nickel salt, comprising the step of electrolyzing said nickel electrolyte in the presence of a reduced triphenylmethane dye obtained by the reaction of the corresponding triphenylmethane dye with a reducing agent comprising zinc powder and a mineral acid, and a holding agent selected from the group consisting of sodium bisulfite and sodium hydrosulfite.

8. A bath for electrodepositing nickel from a nickel electrolyte comprising an aqueous acid solution of a nickel salt comprising, a nickel electrolyte and a reduced triphenylmethane dye obtained by the reaction of the corresponding triphenylmethane dye with a reducing agent comprising zinc powder and hydrochloric acid, and a holding agent selected from the group consisting of sodium bisulfite and sodium hydrosulfite.

9. A bath for electrodepositing nickel from an aqueous acid solution of a nickel salt comprising, an aqueous acid solution of a nickel salt and a reduced triphenylmethane dye obtained by the reaction of the corresponding triphenylmethane dye with a reducing agent comprising zinc powder and hydrochloric acid, and a holding agent selected from the group consisting of sodium bisulfite and sodium hydrosulfite.

LLOYD B. PORTZER. WILLIAM C. IEITENBERGER.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Lind et a1 Apr, 23, 1940 OTHER REFERENCES Number 

1. A METHOD OF ELECTRODEPOSITING NICKEL FROM A NICKEL ELECTROLYTE COMPRISING AN AQUEOUS ACID SOLUTION OF A NICKEL SALT, COMPRISING THE STEP OF ELECTROLYZING SAID NICKEL ELECTROLYTE IN THE PRESENCE OF A REDUCED TRIPHENYLMETHANE DYE OBTAINED BY THE REACTION OF THE CORRESPONDING TRIPHENYLMETHANE DYE WITH A REDUCING AGENT COMPRISING ZINC POWDER AND HYDROCHLORIC ACID, AND A HOLDING AGENT SELECTED FROM THE GROUP CONSISTING OF SODIUM BISULFITE AND SODIUM HYDROSULFITE. 